Foamed beverages such as espresso, cappuccino and latte prepared from dispensing machines are becoming more and more popular. Methods of preparation of such products from a predosed capsule are also known. The principle of using pre-metered and pre-packed portions of coffee or the like for the preparation of coffee or other beverages has the advantage of facilitating the preparation of the beverage while ensuring that the dose-to-dose quality and strength of the beverage remains constant for the same preparation conditions (dosage, temperature, pressure, time. etc . . . ). It also provides more convenience to the user. The capsule usually sits in a leak-tight enclosure of a special coffee type machine and hot water is passed through the capsule under pressure. The use of roast-and-ground powder is widely utilized commercially in capsules that perforate under the building-up of pressure to release the extracted liquid. Attempts have been made to develop systems of preparation of beverages from a disposable capsule containing soluble powder.
WO 02076270 describes a unit for preparing beverages from soluble products. This unit comprises a seat designed to receive a disposable cartridge comprising at least one inlet port for a suspension fluid to enter the cartridge, and at least one outlet port for the delivery of the beverage. The unit further comprises at least one throttling arrangement to give the beverage a laminar flow as it is released from the cartridge. In such a system, a piercing member deeply enters the capsule, thus reducing the volume available for diluting fluid and the soluble powder mixing within the capsule. The narrow outlet port created by the throttling arrangement also prevents the outflow of larger particles or clots of soluble product that have not yet dissolved. Therefore, a significant amount of powder tends to accumulate in contact with the piercing member and does not dissolve during the mixing phase with water. Furthermore, according to the description of the throttling arrangement, the portion of the piercing member entering the capsule has a shape and dimensions substantially equal to those of the capsule outlet port. This means that manufacturing of the capsule and of the piercing member have to be very precise, because any variation in dimensions lead to variations in terms of water flowing speed or pressure in the capsule, and these lead to variations in beverage quality.
The problem met with this existing system comes from the fact that a large portion of the piercing member enters the capsule and occupies too much of the volume of the capsule. This reduces the space available for mixing with water and shearing, causing some undissolved powder to remain dry and stuck to the portion of the piercing member that entered the capsule. Undissolved powder is of course not available for the mixing, and beverages will have less taste or will be less foamy than they otherwise would be if the powder was entirely and homogeneously mixed with water. This also causes variations in the quality of the beverages depending on the quantity of powder dissolved which participates to the mixing and foaming.
The present invention now overcomes these problems.